Canon NP6317 Service Manual page 192

CHAPTER 10 TROUBLESHOOTING
6. Fogging (overall)
Cause/Problem
Procedure
area
1
Dirt on the 2
scanner
Pre-exposure 3
lamps
DC controller 4
PCB
High-voltage 5
transfomer
DC controller
PCB
7. Fogging in paper feed direction
8. Dark lines (broad lines in paper feed direction)
Cause/Problem
Procedure
area
Primary co- 1
rona assembly
Scanner 2
Pre-exposure 3
lamps
Feed roller
10-28
Check
Does the image quality improve after the
basic adjustment procedure is followed?
Does the image improve after the scanning
lamp, reflectors, mirrors, lens and dust-
proofing glass are cleaned?
Does the pre-exposure lamp go ON during
copying?
Set the meter to the 30VDC range and
measure the voltage between J307-6 (+)
and J307-7 (-) of the DC controller PCB.
Is the voltage 10V or less during copying
and approx. 16V at other times?
Is the voltage between J307-5 (+) and
J307-7 (-) of the DC controller PCB
approx. 0.6V during copying and approx.
14V at other times?
Check
Does the image quality improve after the
primary corona wires, grid wires, and co-
rona frame are cleaned?
Does the image quality improve when the
scanning lamp, reflectors, lens, mirrors,
and dust-proofing glass are cleaned?
Is the pre-exposure lamp brighter after it is
cleaned?
COPYRIGHT © 1999 CANON INC.
Result
Yes
Yes
No
No
Yes
No
Result
Yes
Yes
Yes
No
CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Action
End.
End.
1.Replace the pre-expo-
sure lamp unit.
2.Replace the DC con-
troller PCB.
Replace the DC control-
ler PCB.
1.Replace the high-volt-
age trans former.
2.Replace the drum unit.
Replace the DC control-
ler PCB.
Action
End.
End.
End.
Clean the feed roller be-
low the developing unit.